The major purpose of this research is to explore systematically the role of arousal mechanisms in relation to the expression of maladaptive stereotype behavior. The particular behavior of concern is body rocking. The population of subjects to be sampled will be retarded adults and children. Physiological measures include heart rate, respiratory rate and galvanic skin response. Initial studies will be conducted to determine how fluctuations in organism arousal relate to stereotyped movements. A second series to studies is designed to induce alterations in arousal state. In a third series of studies the subject will be given the opportunity to control the onset and intensity of external stimulation, sound and light. The primary analysis will be based on the concepts of spectral analysis.